My favourite campaign was the Alien. Although it was quite short, i enjoyed hunting the 'Prey' and being stealthy. Finding out how to get to the humans you have to infect was good too as some of them would kill themselves if they saw you. The boss was suitable tough too unlike the human and Predator bosses.

Humans were second best, a standard shooter but it had that edgy 'they're coming out the walls' feel especially in the earlier stages where you had little bullets and ran out quickly. It slowly got easier as you got better weapons but it was still balls to the wall shooter action. Great fun.

Predator was a bit meh, i played this campaign last as i heard it was the best but it's just a cross between a sneaky alien bit at the start when you don't have weapons and then onto a shooter nearer the end. Eventually you get some top weaponry and then your a walking tank throwing everything but the kitchen sink at things. It's also the easiest campaign.

Go rent it if you havn't played it yet, it's quite easy and short, but if you loved the movies this is definitive stuff.